Color filter array having a yellow filter layer

ABSTRACT

A color filter array having a yellow filter layer on a substrate wherein the yellow filter layer comprises a pyridone azo dye having its absorption maximum at a wavelength of 400 to 500 nm; and has a transmittance at a wavelength of 450 nm of 5% or less, that at 535 nm of 80% or more and that at 650 nm of 90% or more is provided; the color filter array shows excellent spectroscopic characteristics with respect to yellow light, is capable of forming a pattern with a short time exposure and has a yellow filter layer excellent in light fastness; and a photosensitive resin composition with which a pattern can be formed with a short time exposure is also provided.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to color filter arrays for solid-state image devices or liquid crystal display devices, and to a method for producing the same.

[0002] As a color filter array formed on a device such as asolid-state image device or a liquid crystal display device, there has been known a color filter array (2) constituted of a yellow filter layer (Y), a magenta filter layer (M), and a cyan filter layer (C) formed so as to be adjoining to each other in the same plane of a substrate (1) (FIG. 1). In the color filter array (2), the filter layers (Y), (M), (C) are arranged in a striped pattern (FIG. 2) or a lattice-like pattern (mosaic) (FIG. 3).

[0003] A variety of processes for producing such color filter array have been proposed. Among them, so-called “color resist method” is in wide practical use. In the color resist method, the patterning is effected by exposing a photosensitive resin composition comprising colorants to light and developing, and the patterning is repeated in sequence in the required times.

[0004] As the photosensitive resin composition which is employed in the color resist method, those employing pigments as colorants are in wide use. However, such pigments are not suitable for the formation of fine or minute patterns, for they are granular and do not dissolve in developers, and developing residue is generated.

[0005] As a photosensitive resin composition for obtaining a finely patterned color filter array, a photosensitive resin composition employing dyes as colorants has also been known. For example, Japanese Patent Application Laid-Open No. 6-75375 discloses a negative photosensitive resin composition comprising dyes, and Japanese Patent Publication No. 7-111485 discloses a positive photosensitive resin composition comprising 10 to 50%, on a dry weight basis, of a dye soluble in the solvent used in the positive photosensitive resin composition. (Hereinafter, “JP-A-” is used for indicating Japanese Patent Application Laid-Open, and “JP-B-” is used for indicating Japanese Patent Publication.)

[0006] Colorants comprised in photosensitive resin compositions used for producing color filter arrays, such as those described above, are required to have the following two properties.

[0007] (1) Good transmittance property to the exposure light, that is, having high transmittance to the exposure light used for forming the pattern and capable of forming a pattern with a short time exposure.

[0008] (2) Good light fastness, that is, no burn-in due to the decolorization of dyes under normal operating conditions

[0009] However, none of the dyes employed in conventional photosensitive resin compositions has both of the above-described two properties.

[0010] For example, as a dye to be incorporated in a yellow film layer, a pirazolone azo dye (C.I. Solvent Yellow 88) is described in Japanese Patent Publication No. 7-111485. (Hereinafter, “JP-A-” is used for indicating Japanese Patent Application Laid-Open, and “JP-B-” is used for indicating Japanese Patent Publication.) However, this dye exhibits high absorption of visible ray and near ultra violet ray, such as i-line and g-line, and use of this dye makes the exposure time longer. According to JP-B-7-111485, the exposure time is 20 second to form a yellow filter layer using the dye.

[0011] A colorant exhibiting a small absorption of visible ray and near ultra violet ray. However, generally colorants exhibiting a small absorption of visible ray and near ultra violet ray is not satisfactory in light fastness. Further, such a dye has low solubility in a photosensitive resin composition, and a photosensitive resin composition containing the dye at a high concentration cannot be easily obtained easily.

[0012] Therefore, it has been difficult to manufacture a color filter array having a practical yellow filter layer.

[0013] The inventors of the present invention have made intensive and extensive studies to develop a color filter array having a yellow filter layer having good transmittance property, which enables to form the layer in a short time, as well as good light fastness. As a result, they have found that the use of a specific dye enables the formation of a yellow filter layer satisfactory in light fastness with a short exposure time. The present invention was accomplished based on this finding.

SUMMARY OF THE INVENTION

[0014] The present invention provides a color filter array having a yellow filter layer on a substrate wherein the yellow filter layer comprises

[0015] a pyridone azo dye (hereinafter, referred to as “dye (I)”) having its absorption maximum at a wavelength of 400 to 500 nm; and

[0016] has a transmittance at a wavelength of 450 nm of 5% or less, that at 535 nm of 80% or more and that at 650 nm of 90% or more.

[0017] The present invention also provides a process for producing the color filter array.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [FIG. 1]

[0019]FIG. 1 is a schematic view showing a cross-section of a color filter array in which a yellow filter layer, a magenta filter layer, and a cyan filter layer are provided in the same plane of a substrate.

[0020] [FIG. 2]

[0021]FIG. 2 is a plane schematic view of a color filter array provided with a yellow filter layer, a magenta filter layer, and a cyan filter layer arranged in a striped pattern.

[0022] [FIG. 3]

[0023]FIG. 3 is a plane schematic view of a color filter array provided with a yellow filter layer, a magenta filter layer, and a cyan filter layer arranged in amosaic pattern.

[0024] [FIG. 4]

[0025]FIG. 4 is a plane schematic view of the color filter array obtained in Example 1.

[0026] [FIG. 5]

[0027]FIG. 5 is a plane schematic view of the color filter array obtained in Example 1.

[0028] [Description of Reference Numerals]

[0029] 1: substrate

[0030] 2: color filter array

[0031] Y: yellow filter layer

[0032] M: magenta filter layer

[0033] C: cyan filter layer

EMBODIMENT OF THE INVENTION

[0034] As the substrate used in the color filter of the present invention, a silicon wafer and a transparent inorganic glass plate are exemplified. On the silicone wafer, a charge coupled device may be formed.

[0035] The color filter array of the present invention has a yellow filter layer on its substrate.

[0036] The yellow filter layer comprises a dye (I) having its absorption maximum at a wavelength of 400 to 500 nm. Concrete examples of the dye (I) include compounds represented by the general formula (I):

[0037] wherein R¹⁰ represents an alkyl group having 2 to 10 carbon atoms; R¹¹, R¹², and R¹⁴ each independently represents hydrogen atom, methyl group, hydroxyl group, or cyano group; and R¹³ represents an alkyl group having 1 to 4 carbon atoms. By incorporating such a dye, a yellow filter layer having a transmittance at a wavelength of 450 nm of 5% or less, that at 535 nm of 80% or more and that at 650 nm of 90% or more can be obtained.

[0038] Examples of the alkyl group having 2 to 10 carbon atoms and represented by R¹⁰ in the general formula (II) include ethyl group, propyl group, n-hexyl group, n-nonyl group, n-decyl group, n-dodecyl group, 2-ethylhexyl group, 1,3-dimethylbutyl group, 1-methylbutyl group, 1,5-dimethylhexyl group, and 1,1,3,3-tetramethylbutyl group. Examples of the alkyl group having 1 to 4 carbon atoms and represented by R¹³ include methyl group, ethyl group, propyl group, and butyl group.

[0039] Examples of the dye (I) include C.I. Solvent Yellow 162. These are used singly or in combination. These dyes (I) have their absorption maximum at a wavelength within the range of from 400 to 500 nm, and have low absorption of i-line and g-line.

[0040] For improving light fastness and controlling the color, that is, control of its spectroscopic characteristics, other dyes may be incorporated into the yellow filter layer. One kind of the other dye may be used or two or more of them may be used in combination.

[0041] The transmittance of the yellow filter layer is 5% or less at a wavelength of 450 nm, 80% or more at 535 nm and 90% or more at 650 nm.

[0042] The color filter array of the present invention can be produced by an ordinary color resist method. For example, it can be produced by a process comprising the step of patterning a photosensitive resin composition comprising colorants. The photosensitive resin composition comprises the dye (I).

[0043] The photosensitive resin composition may be a positive photosensitive resin composition or a negative photosensitive resin composition.

[0044] The positive photosensitive resin composition of the present invention comprises, for example, a photoactive compound and an alkali-soluble resin in addition to the above-described dyes.

[0045] A photoactive compound used in conventional photosensitive resin compositions can be used in the positive photosensitive resin composition of the present invention. Examples thereof include esters of phenolic compounds with o-naphthoquinonediazide sulfonates. Examples of the phenolic compounds include compounds represented by the chemical formula (10).

[0046] As the o-naphthoquinonediazide sulfonates, o-naphthoquinonediazi de-5-sulfonate and o-naphthoquinonediazide-4-sulfonate can be exemplified.

[0047] The term “alkali-soluble resin” refers to resins that dissolve in alkaline developers, and any alkali-soluble resin similar to those used in conventional photosensitive resin compositions can be employed. Examples of such alkali-soluble resins include novolak resins such as those of p-cresol novolak resins, novolak resins of p-cresol and m-cresol; novolak resins having the structure represented by the formula (20):

[0048] ; polyvinylphenol; and copolymers of styrene with vinylphenol. Preferably, a novolak resin is employed as the alkali-soluble resin.

[0049] The amounts of the dyes, the photoactive compound, and the alkali-soluble resin comprised in the photosensitive resin composition are usually 10 to 50 parts by weight, 10 to 50 parts by weight, and 3 to 50 parts by weight, per a total of 100 parts by weight of the dyes, photoactive compound, and alkali-soluble resin, respectively.

[0050] Into the positive photosensitive resin composition, a curing agent may be incorporated. Incorporation of the curing agent improves the mechanical strength of the pattern formed by using the photosensitive resin composition.

[0051] As the curing agent, usually, a heat curing agent which is cured through heating is employed. Examples of the heat curing agent include compounds represented by the general formula (30):

[0052] wherein Q¹, Q², Q³, and Q⁴ each independently represents hydrogen atom, a hydroxyalkyl group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms and substituted with an alkoxyl group having 1 to 4 carbon atoms; Z represents phenyl group or a group represented by the general formula (31):

Q⁵Q⁶N—  (31)

[0053] wherein Q⁵ and Q⁶ each independently represents hydrogen atom, a hydroxyalkyl group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms and substituted with an alkoxyl group having 1 to 4 carbon atoms

[0054] with the proviso that at least one of Q¹ to Q⁶ is a hydroxyalkyl group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms and substituted with an alkoxyl group having 1 to 4 carbon atoms.

[0055] Examples of the hydroxyalkyl group having 1 to 4 carbon atoms include hydoxymethyl group, hydroxyethyl group, hydroxypropyl group, and hydroxybutyl group. Examples of the alkyl group having 1 to 4 carbon atoms and substituted with an alkoxyl group having 1 to 4 carbon atoms include methoxymethyl group, methoxyethyl group, ethoxyethyl group, and propoxybutyl group.

[0056] An example of the compound represented by the general formula (30) is hexamethoxymethylmelamine.

[0057] Moreover, compounds of the following chemical formulae (32) to (37) can be used as the curing agent in the positive photosensitive resin composition of the present invention, for example.

[0058] When the curing agent is used, its content is usually not less than 10 parts by weight and not more than 35 parts by weight per a total of 100 parts by weight of the dyes, the photoactive compound, and the alkali-soluble resin.

[0059] The positive photosensitive resin composition of the present invention is usually diluted with a solvent.

[0060] The solvent is suitably selected according to the solubilities of the dye (I), photoactive compound, alkali-soluble resin, and curing agent. For example, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol dimethyl ether, ethylene glycol monoisopropyl ether, propylene glycol monomethyl ether, N-methylpyrrolidone, γ-butyrolactone, dimethyl sulfoxide, N,N′-dimethylformamide, cyclohexane, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, ethyl acetate, ethyl pyruvate, ethyl lactate, or the like can be employed. These solvents are used either singly or in combination.

[0061] The amount of the solvent to be used is usually about 180 to 400 parts by weight per a total of 100 parts by weight of the dyes, photoactive compound, alkali-soluble resin, and curing agent.

[0062] The negative photosensitive resin composition of the present invention comprises, for example, a photoreactive acid generator, a curing agent, and an alkali-soluble resin, in addition to the dyes described above.

[0063] A photoreactive acid generator use in conventional negative photoreactive resin compositions can be employed as the photoreactive acid generator used in the negative photosensitive resin composition of the present invention. Examples thereof include compounds represented by the general formula (40):

[0064] wherein Q⁷ represents an alkyl group having 1 to 3 carbon atoms, and Q⁸ represents a phenyl group substituted with an alkyl group having 1 to 3 carbon atoms or a phenyl group substituted with an alkoxyl group having 1 to 3 carbon atoms.

[0065] Examples of the alkyl group having 1 to 3 carbon atoms represented by Q⁷ include methyl group, ethyl group, and propyl group. An example of the phenyl group substituted with an alkyl group having 1 to 3 carbon atoms and represented by Q⁸ is o-isopropylphenyl group. Examples of the phenyl group substituted with an alkoxyl group having 1 to 3 carbon atoms include p-methoxyphenyl group, p-ethoxylphenyl group, and p-propoxyphenyl group.

[0066] Moreover, compounds represented by the chemical formulae (41) to (47):

[0067] can also be used as the photo acid generator, for example.

[0068] As the curing agent, a heat curing agent which is cured through heating is usually employed as in the case of conventional negative photosensitive resin composition. The heat curing agents listed above as examples for the positive photosensitive resin composition can also be employed in the negative photosensitive resin composition of the present invention.

[0069] The alkali-soluble resins listed above as examples for the positive photosensitive resin composition can also be employed in the negative photosensitive resin composition of the present invention, as in the case of conventional negative photosensitive resin composition.

[0070] The amounts of thephoto acid generator, curing agent, and alkali-soluble resin comprised in the negative photosensitive resin composition per a total of 100 parts by weight of the dyes, photoreactive acid generator, curing agent, and alkali-soluble resin are as follow. The content of the dyes is usually about 15 to 40 parts by weight, and that of the photo acid generator is usually 0.3 to 5 parts by weight. The amount of the curing agent to be used is usually 10 to 25 parts by weight, and the content of the alkali-soluble resin is usually 20 to 75 parts by weight.

[0071] The negative photosensitive resin composition is usually diluted with a solvent.

[0072] The solvent is selected according to the solubilities of the dye (I), photo acid generator, alkali-soluble resin, and curing agent, especially according to the solubilities of the dye (I), dye (II), dye (III), and dye (IV). The solvent listed above as examples for the positive photosensitive resin composition can be employed. The amount of the solvent to be used is usually about 180 to 400 parts by weight per a total of 100 parts by weight of the dyes, photo acid generator, curing agent, and alkali-soluble resin.

[0073] Since the above-described photosensitive resin composition employs the dye (I) as its colorant, almost no precipitate is generated even if the composition is stored for a long period of time. Consequently, the composition can be applied onto the substrate practically without irregularities. This makes it possible to provide a color filter array having a yellow filter layer with a pattern of about 0.5 to 2 μm in thickness and about 2 to 20 μm in length of each side.

[0074] The patterning is effected, for example, by providing a coat of the above-described resin composition on a substrate, exposing the coat to light, and then developing.

[0075] The coat is provided on the substrate by applying a diluted photosensitive resin composition thereto. The composition is usually applied by spin coating. After the composition has been applied onto the substrate, the coat is heated up to, for example, about 80 to 130° C. to evaporate the solvent comprised therein. Thus, a coat of the photosensitive resin composition is obtained.

[0076] Thereafter, the coat is exposed to light. The exposure to light involves the use of a mask pattern corresponding to the desired pattern, and is effected by irradiating the coat with a beam through the mask pattern. As the beam for the exposure of the coat to light, for example, g-ray, i-ray, or the like can be employed. Such an exposure equipment as the g-ray stepper or i-ray stepper may be employed for the exposure.

[0077] Using the photosensitive resin composition, a pattern can be formed with a short time exposure.

[0078] When a negative photosensitive resin composition is used, the coat is heated after the exposure to light. When the positive photosensitive resin composition is used, the coat may be heated after the exposure or may not be heated. On heating the coat, the heating temperature is, for example, about 80 to 150° C.

[0079] After having been exposed to light, the coat is subjected to development. The development is effected by immersing the substrate provided with the coat in a developer, as in the case of the use of an ordinary photosensitive resin composition. Developer used for patterning conducted by using a conventional photosensitive resin composition can also be employed in patterning in the present invention. A color filter array having a yellow filter layer defined in the desired pattern can be obtained by taking the substrate out of the developer and then washing with water to remove the developer.

[0080] When a positive photosensitive resin composition is used, after having been washed with water, the substrate may be subjected to ultraviolet ray irradiation. Irradiation of ultraviolet rays can decompose the remaining photo active compound. Moreover, when the photosensitive resin composition comprises a heat curing agent, the substrate may be heated after having been washed with water. By heating, the mechanical strength of the formed yellow filter layer can be improved. The heating temperature is usually not lower than 160° C. and not higher than 220° C. Usually, the heating temperature is not higher than the decomposition temperatures of the dyes.

[0081] When a negative photosensitive resin composition is used, the substrate may be heated after having been washed with water. By heating, the mechanical strength of the formed yellow filter layer is improved. The heating temperature is usually not lower than 160° C. and not higher than 220° C. Usually, the heating temperature is not higher than the decomposition temperatures of the dyes.

[0082] Thus, a yellow filter layer in the desired pattern is formed. Transmittances of the yellow filter layer thus formed are preferably 5% or less at a wavelength of 450 nm and 80% or more at 535 nm.

[0083] The other filter layers, that is, a magenta filter layer and a cyan filter layer are formed in the same plane of the substrate which has been provided with the yellow filter layer, according, for example, to a conventional manner. When employing a positive photosensitive resin composition, it is preferred to employ one comprising a curing agent and carry out heating after development, for the strength of the formed yellow filter layer is improved. The yellow filter layer may be formed after the other color filter layers have been provided on the substrate.

[0084] Thus, a color filter array constituted of the yellow filter layer, magenta filter layer, and cyan filter layer that are formed so as to be adjoining to each other in the same plane of the substrate can be obtained.

[0085] The color filter array thus obtained is used for a solid-state image device, a liquid crystal display device, and the like. For instance, in the solid-state image device, if the color filter array is disposed on the front side of its charge-coupled device, color images excellent in color reproductivity can be obtained.

[0086] The color filter array of the present invention shows excellent spectroscopic characteristics and has a yellow filter layer excellent in light fastness. Moreover, since dyes are employed as its colorants, a yellow filter layer less in foreign matter content, and uniform in thickness can be produced with ease. This color filter array is favorably employed for use in a liquid crystal display device or a solid-state image device comprising a charge-coupled device.

[0087] Hereinafter, the present invention will be described in more detail based on Examples, but these should by no means be construed as defining the scope of the present invention.

EXAMPLE 1

[0088] After 36 parts by weight of C.I. Solvent Yellow 162 as the dye (I), 27 parts by weight of the ester of a phenolic compound represented by the chemical formula (10) with o-naphthoquinonediazide-5-sulfonate, as the photoactive compound, 18 parts by weight of a novolak resin of p-cresol as the alkali-soluble resin (weight average molecular weight in terms of polystyrene: 6,000), 20 parts by weight of hexamethoxymethylmelamine as the curing agent, and 400 parts by weight of ethyl lactate as the solvent had been mixed and dissolved, the resulting mixture was filtrated with a membrane filter having a pore size of 0.1 μm to provide a positive photosensitive resin composition.

[0089] A coat was formed by applying the positive photosensitive resin composition obtained above onto a substrate (silicon wafer) by spin coating and heating at 100° C. for 1 minute to evaporate ethyl lactate therefrom. The coat had been exposed to light by irradiation of i-ray through a mask pattern using an exposure equipment (“Nikon NSR i7A” manufactured by Nikon Corp.). Then, the pattern was developed by immersing the coated substrate in a developer (“SOPD” manufactured by Sumitomo Chemical Co., Ltd.) at 23° C. for 1 minute. After the development, the substrate was washed with water, dried, irradiated with ultraviolet rays, and heated to 180° C. for 3 minutes to give a color filter array having a yellow filter layer in a striped-pattern (FIG. 4). The yellow filter layer has a line width of 1.0 μm and a thickness of 0.7 μm.

[0090] Thereafter, except using a different mask pattern, the same procedure as above was repeated to give a color filter array having a yellow filter layer formed in a mosaic pattern (FIG. 5). The yellow filter layer has a line width of 2.0 μm and a thickness of 0.7 μm.

[0091] Except that a transparent glass plate was employed as the substrate in place of a silicon wafer and that the pattern was developed without being exposed to light, the same procedure as above was repeated to give a yellow filter layer formed in a thickness of 0.7 μmall over the substrate.

EXAMPLE 2

[0092] Except for using 18 part by weight of C.I. Solvent Yellow 162 as the dye (I) and 18 part by weight of C.I. Solvent Yellow 82 as the other dye in place of 36 parts by weight of C.I. Solvent Yellow 162, the same procedure as in Example 1 was repeated to give a color filter array having a striped-pattern yellow filter layer with a line width of 1.0 μm and a thickness of 0.7 μm (FIG. 4), a color filter array having a mosaic-pattern yellow filter layer with a line width of 2.0 μm and a thickness of 1.1 μm, and a yellow filter layer formed in a thickness of 1.1 μm all over the substrate.

EXAMPLE 3

[0093] After 18 part by weight of C.I. Solvent Yellow 162 as the dye (I), 0.5 parts by weight of the compound represented by the chemical formula (50):

[0094] as the photo acid generator, 44 parts by weight of a novolak resin of p-cresol as the alkali-soluble resin (weight average molecular weight in terms of polystyrene: 5,000), 20 parts by weight of hexamethoxymethylmelamine as the curing agent, and 400 parts by weight of ethyl lactate as the solvent had been mixed and dissolved, the resulting mixture was filtrated with a membrane filter having a pore size of 0.1 μm to provide a negative photosensitive resin composition.

[0095] A coat was formed by applying the negative photosensitive resin composition obtained above onto a substrate (silicon wafer) by spin coating and heating at 100° C. for 1 minute to evaporate ethyl lactate therefrom. The coat had been exposed to light by irradiation of i-ray through a mask pattern using an exposure equipment (“Nikon NSR i7A” manufactured by Nikon Corp.), followed by heated at 120° C. for 1 minute. Then, the pattern was developed by immersing the coated substrate in a developer (“SOPD” manufactured by Sumitomo Chemical Co., Ltd.) at 23° C. for 1 minute. After the development, the substrate was washed with water, dried, irradiated with ultraviolet rays, and heated to 180° C. for 3 minutes to give a color filter array having a yellow filter layer in a striped-pattern. The yellow filter layer has a line width of 1.0 μm and a thickness of 0.7 μm.

[0096] Thereafter, except using a different mask pattern, the same procedure as above was repeated to give a color filter array having a yellow filter layer formed in a mosaic pattern. The yellow filter layer has a line width of 2.0 μm and a thickness of 0.7 μm.

[0097] Except that a transparent glass plate was employed as the substrate in place of a silicon wafer and that the exposure to light was conducted without using the mask pattern, the same procedure as in Example 1 was repeated to give a yellow filter layer formed in a thickness of 0.7 μm all over the substrate.

EXAMPLE 4

[0098] A photosensitive resin composition for forming a magenta filter layer, a photosensitive resin composition for forming a cyan filter layer, and a photosensitive resin composition for forming a yellow filter layer were prepared according to the respective blending formulations shown below. (Photosensitive resin composition for forming a magenta filter layer) Novolak resin 36 parts by weight o-naphthoquinonediazide-4-sulfonate 30 parts by weight Hexamethoxymethylmelamine 17 parts by weight Ethyl lactate 280 parts by weight N,N′-dimethylformamide 120 parts by weight A compound represented by the 18 parts by weight chemical formula (51) (61)

(Photosensitive resin composition for forming a cyan filter layer) Novolak resin 19 parts by weight o-naphthoquinonediazide-4-sulfonate ester 43 parts by weight Hexamethoxymethylmelamine 16 parts by weight Ethyl lactate 210 parts by weight N,N′-dimethylformamide 90 parts by weight C.I. Solvent Blue 67 23 parts by weight (Photosensitive resin composition for forming a yellow filter layer) Novolak resin 18 parts by weight o-naphthoquinonediazide-4-sulfonate ester 27 parts by weight Hexamethoxymethylmelamine 20 parts by weight Ethyl lactate 280 parts by weight N,N′-dimethylformamide 120 parts by weight C.I. Solvent Yellow 162 18 parts by weight C.I. Solvent Yellow 82 18 parts by weight

[0099] The photosensitive resin composition for forming a yellow filter layer prepared above had been applied onto a silicon wafer provided with a charge-coupled device by spin coating. Then, its solvent was evaporated off on a baking plate at 100° C.

[0100] Thereafter, using an i-ray stepper exposure equipment (“Nikon NSR2205 i12D” manufactured by Nikon Corp.), the substrate was irradiated with an ultraviolet ray of a wavelength of 365 nm through a reticle (2,000 mJ/cm²). Then, the substrate was subjected to development by a developing agent (an aqueous solution containing 30 g of tetramethylammonium hydroxide per 1,000 cm³). After the exposed portion had been removed, the substrate was washed with pure water. Thereafter, using a low-pressure mercury lamp (3,000 mJ/cm²), ultraviolet rays were irradiated all over the substrate, and the substrate was then heated on a baking plate at 180° C. for 10 minutes to form a yellow filter layer.

[0101] Except for using the photosensitive resin composition for forming a magenta filter layer prepared above instead of the photosensitive resin composition for forming a yellow filter layer, the same procedure as above was repeated to form a magenta filter layer (FIG. 6(b)).

[0102] Except for using the photosensitive resin composition for forming a cyan filter layer prepared above, the same procedure as above was repeated to form a cyan filter layer and consequently a color filter array.

[0103] A microlens was formed on the color filter array in a conventional manner to give a solid-state image device. The thickness of the yellow filter layer of the color filter array at the solid-state image device was 0.7 μm. The color filter array at this solid-state image device showed good spectroscopic characteristics.

[0104] In the same manner as that described above, a yellow filter layer (thickness: 0.7 μm) was formed all over a quartz wafer.

Comparative Example 1

[0105] Except for using 20 of parts by weight of the compound represented by the chemical formula (52):

[0106] wherein R⁵⁰ represent a group represented by the following formula (53):

[0107] 10 of parts by weight of the compound represented by the chemical formula (54):

[0108] wherein R⁵¹ represent a group represented by the following formula (55):

[0109] 6 of parts by weight of the compound represented by the chemical formula (56):

[0110] wherein R ⁵² represent a group represented by the formula (55)

[0111] in place of C.I. Solvent Yellow 162, the same procedure as in Example 1 was repeated to give a color f ilter array having a striped-pattern yellow filter layer with a line width of 1.0 μm and a thickness of 1.1 μm, a color filter array having a mosaic-pattern yellow filter layer with a line width of 2.0 μm and a thickness of 1.1 μm, and a yellow filter layer formed in a thickness of 1.1 μm all over the substrate.

[0112] Evaluation

[0113] (1) Exposure Time

[0114] The exposure time required to form lines of 1.0 μm in each of Examples and Comparative Example is shown in Table 1.

[0115] (2) Spectroscopic Characteristics

[0116] The color filter arrays each provided with a yellow filter layer all over its substrate and obtained in Examples and Comparative Example were subjected to measurement of light transmittance at 450 nm, 535 nm, and 650 nm. The results are shown in Table 2.

[0117] (2) Light Fastness

[0118] An ultraviolet ray-blocking filter (“colored optical glass L38” manufactured by Hoya Corp. Capable of blocking light of a wavelength of 380 nm or shorter) was disposed in front of each of the color filter arrays obtained in Examples and Comparative Example and provided with a yellow filter layer all over its substrate, followed by irradiating light at 1,000,000 1×·hour. “Sun tester XF 180 CPS” manufactured by Shimadzu Corp. was employed as the light source. The light transmittance of each color filter array after the irradiation was measured at a wavelength of 450 nm, 535 nm, and 650 nm. The results are shown in Table 3. TABLE 1 Exposure time (msec) Example 1 400 Example 2 600 Example 3 250 Comparative 2000  example 1

[0119] TABLE 2 Light transmittance (%) Wavelength 450 535  650 (nm) Example 1 0.2 95 100 Example 2 0.6 84  98 Example 3 0.5 95 100 Comparative 7 93  98 example 1

[0120] TABLE 3 Light transmittance (%) Wavelength 450  535  650 (nm) Example 1 2 98 100 Example 2 2 87 100 Example 3 5 98 100 Comparative 19  94  99 example 1 

What is claimed is:
 1. A color filter array having a yellow filter layer on a substrate wherein the yellow filter layer comprises a pyridone azo dye having its absorption maximum at a wavelength of 400 to 500 nm; and has a transmittance at a wavelength of 450 nm of 5% or less, that at 535 nm of 80% or more and that at 650 nm of 90% or more.
 2. A process for producing a color filter array having a yellow filter layer on a substrate which comprises the step of patterning a photosensitive resin composition comprising a pyridone azo dye having its absorption maximum at a wavelength of 400 to 500 nm to form the yellow filter layer having a transmittance at a wavelength of 450 nm of 5% or less, that at 535 nm of 80% or more and that at 650 nm of 90% or more.
 3. A photosensitive resin composition comprising a pyridone azo dye having its absorption maximum at a wavelength of 400 to 500 nm.
 4. The photosensitive resin composition according to claim 3 which further comprises a photoactive compound, and an alkali-soluble resin, and wherein the amounts of the dyes, the photoactive compound, and the alkali-soluble resin are 10 to 50 parts by weight, 10 to 50 parts by weight, and 3 to 50 parts by weight, per a total of 100 parts by weight of the dyes, photoactive compound, and alkali-soluble resin, respectively.
 5. The photosensitive resin composition according to claim 3 which further comprises a curing agent, and wherein the amount of the curing agent is not less than 10 parts by weight and not more than 35 parts by weight per a total of 100 parts by weight of the dyes, the photoactive compound, and the alkali-soluble resin.
 6. The photosensitive resin composition according to claim 3 which further comprises photo acid generator, curing agent, and an alkali-soluble resin, and wherein the amounts of the dyes, the photo acid generator, the curing agent, and the alkali-soluble resin are about 15 to 40 parts by weight, 0.3 to 5 parts by weight, 10 to 25 parts by weight, and 20 to 75 parts by weight, per a total of 100 parts by weight of the dyes, photoreactive acid generator, curing agent, and alkali-soluble resin, respectively. 